The invention relates to a threaded spindle with a drive part, which has a longitudinal axis and is mounted by a first journal, and having a threaded part, which likewise has a longitudinal axis, and having a threaded nut, which is mounted to a second journal and in which the threaded part is guided.
Such a threaded spindle with a threaded nut is commonly embodied in prior art as a ball screw, which may be used in the field of flap and door opening systems and primarily in the field of vehicles. In vehicles it can be used, for example in the vehicle brakes. Here, the drive part is set in motion with the help of an electric motor. This results in a longitudinal motion of the threaded nut being generated, which operates a brake piston and this way acts as the locking device for a vehicle brake. The threaded part contacts via balls the threaded nut. In the spindle/ball journal arrangement known from the document DE 101 50 803 A1, thus in a ball screw drive, a jamming may occur of the threaded nut and the threaded spindle when the threaded nut is moved back. In order to prevent this it is known from the document WO 99/45292 A1 to provide the threaded nut with a projection at its face adjacent to the drive part, which can be made to contact a stop embodied at the drive part, acting in the circumferential direction, and thus can be brought to a certain alignment in reference to the thread of the threaded spindle.
Although in FIGS. 2 and 3 the document U.S. Pat. No. 5,711,709 shows a threaded spindle with a drive part, which has a longitudinal axis, and shows a threaded part, which also has a longitudinal axis, and with a threaded nut in which the threaded part is guided, with the drive part and the threaded part being embodied as separate parts, here, which are connected to each other in an articulate fashion by way of plugging together, so that a radial mutual off-set or an inclination of the longitudinal axes of the drive part and the threaded part can be compensated, in spite thereof it cannot be excluded here that the ball drive jams during operation.
The primary problem in such ball drives is namely given such that in a faulty alignment of the two journals or in case of a distortion of the threaded spindle, thus a radial mutual off-set or incline of the longitudinal axes of the drive part and the threaded part, the ball drive may jam during operation and thus may be hindered from fulfilling its intended purpose, they are subject to considerably higher wear and tear, and may show a worsened effectiveness.